Tetraalkyl-bis-aminomethyl disiloxane as a sensitizer for silver halide in the emulsion or developer bath

ABSTRACT

In producing photographic images, increasing the sensitivity without increase of fog by using tetraalkyl-bis-aminomethyl disiloxane either in the silver halide emulsion or in the developing bath.

United States Patent [72] Inventors Harald Huckstadt Koeln-Stammheim; Wolfgang Ilimmelmann, Koeln- Stammheim; Wilhelm Saleck, Schildgen; August Randolph, Leverkusen; Erwin Ranz, Leverkusen; Walter Simmler, Koeln- [54] TETRAALKYL-BIS-AMINOMETIIYL DISILOXANE AS A SENSITIZER FOR SILVER IIALIDE IN THE EMULSION 0R DEVELOPER BATH 13 Claims, No Drawings [52] U.S.Cl 96/66.3, 96/107 [51] Int.Cl G03cl/28, G03c 5/30 [50] Field oiSearchm, 96/107, 66.3

[56] References Cited UNITED STATES PATENTS 3,451,819 6/1969 Haugh 96/663 FOREIGN PATENTS 1,030,811 5/1966 GreatBritain 96/107 Primary Examiner- Norman G. Torchin Assistant Examiner- Richard E. Fichter Attorney-Connolly and Hutz ABSTRACT: In producing photographic images, increasing the sensitivity without increase of fog by using tetraalkyl-bisaminomethyl disiloxane either in the silver halide emulsion or in the developing bath.

TETRAALKYL-BIS-AMINOMETHYL DISILOXANE AS A SENSITIZER FOR SILVER HALIDE IN THE EMULSION R DEVELOPER BATH The invention relates to silver halide emulsions, the speed of which is increased by silicone containing amines. These compounds can be present either in the emulsion or in the developer bath.

A number of methods have previously been described for increasing the sensitivity of photographic silver halide emulsions. The incorporation of certain colored compounds or dyes in the emulsions increases the optical range of sensitivity, and for this reason such dyes are commonly referred to as op' tical or spectral-sensitizing dyes. It is also well known to increase the sensitivity of photographic emulsions by addition of sulfur compounds capable of reacting with silver salts to form silver sulfide, or by addition of reducing agents (compounds of these types are also naturally present in gelatin), or with salts of gold or other noble metals, or with combinations of two or more of the aforementioned compounds generally known as chemical sensitizers. Such chemical sensitizers are believed to react with the silver halide to form, on the surface of the silver halide, minute amounts of silver sulfide or of silver or of other noble metals, and these processes are capable of increasing the sensitivity of emulsions by very large factors. The process of chemical sensitization, however, reaches a definite limit beyond which further addition of sensitizer, or of further digestion with the sensitizer present, merely increases the fog of the photographic emulsion leaving the sensitivity constant or even decreasing it.

Other chemical sensitizers are higher polyethylenglycols having a molecular weight of at least 1,500. Lower polyethylenglycols have no or only very small effect on the sensitivity of silver halide emulsions. While the higher polyethylenglycols have a considerable or remarkable sensitization effect, the utility of such compounds is limited by the fact that they cause marked increases in the fog levels of silver halide emulsions. It is known that the fog level increase cannot sufficiently be controlled by the addition of antifoggants to the emulsion.

lt is among the objects of the present invention to increase the general sensitivity or speed of silver halide emulsion layers. A further object is to provide photographic silver halide emulsions and emulsion layers having an increased general sensitivity without concomitant increase in fog level. Other objects will be apparent from the following description of the invention.

By the term general sensitivity it is intended to refer to the sensitivity of photographic emulsions through the whole spec trum. By the term spectral sensitivity it is intended to refer to the sensitivity of the photographic emulsion to light of a certain range of the spectrum.

We now have found that the speed of silver halide emulsions can be increased without concomitant fog formation by tetraalkyl-bis-aminomethyl-disiloxanes. Suitable sensitizers include those of the following formulas:

in which R R R R stand for hydrogen, alkyl containing up to 12 carbon atoms, preferably up to six carbon atoms, cycloalkyl such as cyclohexyl; R and R or R and R. may together represent the ring members necessary for completing a saturated 5-, 6- or 7-membered heterocyclic ring such as a pyrrolidine, morpholine, thiomorpholine, hexamethylene imine or hexahydropyridine ring.

R represents alkyl containing up to six carbon atoms,

preferably methyl.

Particular utility is exhibited by the following compounds:

The preparation of the above compounds has been described in German Auslegeschrift l, 1 96,869.

The preparation of photographic silver halide emulsions includes three separate steps:

1. Emulsification and physical ripening which is also called Ostwald ripening;

2. the freeing of the emulsion of excess water soluble salts, usually by washing with water and drying, and

3. the after ripening which is also called chemical ripening to obtain increased emulsion speed or general sensitivity.

The sensitizers of the present invention can be added to the emulsion before, during or after the chemical ripening or they can be added immediately prior to the casting.

The particular quantity of the sensitizers of the invention used in a given emulsion can vary, depending upon the effects desired, silver content of the emulsion, the silver halide composition etc. Generally they are added in amounts of 5 mg. to 5 g. per liter of emulsion preferably 50 mg. to l g. of emulsion which corresponds from 16 mg. to 16 g. per mol of silver ha lide. The compounds are also effective when they are added to the developer solution in which case they are preferably used in quantities of between approximately 50 mg. and 2 g. per liter of the aqueous developer bath.

The sensitizers can be dissolved in water or a solvent miscible with water or a mixture of water and water-miscible solvents, and added in this form to the emulsion. The solvent is not critical and should be selected so that it should have no harmful effect to the photographic properties of the silver halide emulsion.

The optimum amount for any sensitizer of the present invention can be determined for any particular emulsion by running a series of comparison tests in which the quantity of the sensitizer is varied over a given range. Exposure of the emulsion containing the sensitizer in a manner well-known and measuring of the sensitivity in conventional apparatuses will reveal most advantageous concentrations. Such technique is well understood by those skilled in the art.

The substances according to the invention may be used in any silver halide emulsions. Suitable silver halides are silver chloride, silver bromide or mixtures thereof, which may con tain a small amount of silver iodide of up to mol percent.

The photographic emulsion in which the sensitizers according to the invention are used, can be chemically sensitized by any of the known procedures. They can be sensitized, for example, with sulfur compounds as referred to, e.g. in the book The Theory of the Photographic Process by Mees (1954) pages 149-161.

The emulsions can also be chemically sensitized with salts of noble metal such as gold, ruthenium, rhodium, palladium, iridium and platinum, used in amounts below that which produce any substantial fog. Representative compounds are ammonium chloropalladate, potassium, chloroplatinate, potassium chloroaurite, potassium aurithiocyanate, potassium chloroaurate, auric trichloride and the like. The emulsions can be sensitized with reducing agents, stannous salts or polyamines and the like. The emulsions can also be optically sensitized with cyanine, merocyanine or rhodacyanine dyes.

The emulsions may also be optically sensitized, e.g. with the usual polymethine dyes such as neutrocyanines, basic or acid carbocyanines, rhodacyanines, hemicyanines, styry] dyes, oxonoles and the like. Sensitizers of this type have been described in the work by F. M. Hamer (The Cyanine Dyes and Related Compounds" (1964)).

The emulsions can be stabilized with any of the known stabilizers, e.g. homopolar or salt-type compounds of mercury with aromatic or heterocyclic compounds (for example mercaptotriazoles), simple mercury salts, sulfonium mercury double salts and other mercury compounds. Other suitable stabilizers include azaindenes, especially tetraor pentaazaindenes, in particular those which are substituted with hydroxyl or amino groups. Such compounds have been described in the article by Birr, Z. Wiss. Phot. 47, 2-58 (-1952). Other suitable stabilizers include heterocyclic mercapto compounds, e.g. phenylmercaptotetrazole, quaternary benzothiazole derivatives, benzotriazole and the like. The silver halide emulsion layers may contain any suitable film-forming and waterpermeable colloid as binding agent, such as gelatin but the gelatin can be replaced partially with products like alginic acid and derivatives thereof such as salts, preferably with alkali metals, esters with lower aliphatic alcohols or amides. The gelatin can also be partially replaced with polyvinyl alcohol, polyvinyl pyrrolidone, starch, carboxymethyl cellulose and the like.

The emulsions may be hardened in the usual manner, for example, with formaldehyde or halogen-substituted aldehydes which contain a carboxyl group, such as mucobromic acid, diketones, methanesulfonic acid esters, dialdehydes and the like.

The compounds according to the invention are effective for both black-white emulsions and for color photographic emulsions which contain color couplers.

EXAMPLE 1:

The following substances are added to one liter of a silver iodobromide gelatin emulsion which contains, per liter, 60 g. of silver in the form of silver halide containing 6 mols percent of silver iodide:

600 mg. of saponin as wetting agent 200 mg. of 4-hydroxy-6-methyl-l,3,3a,7-tetraazaindene as stabilizer and 10 ml. of a 10 percent aqueous solution of formaldehyde as hardener.

The emulsion is divided into 3 parts and the following compounds are added per liter of emulsion:

Sample A: Comparison sample without additive Sample B: 0.1 g. of substance IV Sample C: 0.3 g. ofsubstance IV.

p-M'ethylaminophenol 1.0 g. sodium sulfite anhydrous 13.0 g. hydroquinone 3.0 g. sodium carbonate anhydrous 26.0 g. potassium bromide 1.0 g.

water up to 1 liter Table 1 Sample sensitivity 7 fog An increase by 3 denotes double sensitivity or an sensitivity increase of one shutter stop.

EXAMPLE 2 A silver iodo-bromochloride gelatin emulsion containing 60 g. of silver nitrate per kg. in the form ofsilver halide which contains as in example 1 4-hydroxy-6-methyl-l ,3,3a,7- tetraazaindene as stabilizer, saponin as wetting agent and formalin as hardener, is divided into 8 equal parts. Subsequent treatment and the development are carried out as given in example l,

The following substances (per liter of emulsion) are added to the individual parts:

Sample A: Comparison sample without additive Sample B: 100 mg. ofsubstance 1V Sample C: 3.0 g. of compound 1 Sample D: 3.0 g. of compound 11 Sample E: 300 mg. ofcompound 111.

An increase by 3 denotes double sensitivity or a sensitivity increase of one shutter stop.

EXAMPLE 3 A sensitizing dye of the following formula:

is added in an amount of 45 mg./kg. to a mixed emulsion which is composed of percent of a silver iodobromide and percent of silver iodo-bromochloride gelatin emulsion and which has been chemically ripened to optimum sensitivity in known manner using gold and sulfur compounds.

In addition, the following substances were added per liter of emulsion:

g. of (l-(3'-sulfo-4-phenoxy)-phenyl-3-heptadecylpyrazolone as magenta coupler 250 mg. of l,3,3a,7-4-hydroxy-6-methyl-tetraazaindene as stabilizer ml. of a 5 percent aqueous solution of saponin as wetting agent 2.5 ml. of a 30 percent aqueous solution of formaldehyde as hardener.

The above emulsion was divided into 6 equal parts and the substances shown below were added (per liter of emulsion) to the different parts:

Sample A: Comparison sample without additive Sample B: 1.0 g. of Substance I Sample C: 3.0 g. of Substance II Sample D: 3.0 g. of Substance III.

The samples were applied onto a support of cellulose acetate and dried. They are then exposed in a sensitometer customarily employed in the art behind a step wedge and processed in the usual manner. Processing is carried out as follows:

Color development 7 minutes short stop bath 5 minutes rinsing 5 minutes bleaching bath 5 minutes rinsing 5 minutes fixing bath 5 minutes rinsing l0 minutes The color developer bath has the following composition:

Dicthyl-p-phenylenediaminc sulfate 2.75 g. hydroxylaminc sulfate L20 g. sodium sulfite anhydrous 2.00 g. sodium hexametaphosphate 2.00 g. potassium carbonate anhydrous 75.00 g. potassium bromide 2.00 g.

make up to l liter The other treatment baths have the following composition:

Short stop bath The color density of the magenta layers was determined with a Macbeth Quanta Log, Model TD 102" densitometer, placing a green color filter in the path of the measuring light.

Table 3 Sample 5 7 B +3 .9 0.45 0.16 C +0.9 0.39 0.13 D +2.0 0.48 0.12

An increase by 3 denotes double sensitivity or a sensitivity increase of one shutter stop.

EXAMPLE 4 Table 4 Sample S y fog A 0.88 0.07 B +0.$ 0.81 0.07 C +3.7 0.9l 0.09

An increase by 3.0 denotes double sensitivity or a sensitivity increase of one shutter stop.

We claim:

1. In a process for the production of photographic images by exposing and developing a supported silver halide emulsion layer, the improvement according to which the emulsion is sensitized by a tetraalkyl-bis-aminomethyl-disiloxane of the following formula:

in which R R R R represent hydrogen or alkyl having up to 12 carbon atoms; or R and R or R and R, together may represent the ring membersnecessary for completing a pyrrolidine, morpholine, thiomorpholine, hexamethylene, imine or hexahydropyridine;

R stands for alkyl having up to six carbon atoms; in amounts ranging from 5 mg. to 5 g. per liter of emulsion or 50 mg. to 2 g. per liter of the developer bath.

2. The process as defined in claim I, wherein R is methyl.

3. The process of claim 1, wherein the disiloxane has the following formula:

IIsCg CH3 CH3 C1115 Nwm-s Fo-sfFCHFN Hie, on; on. can.

4. The process of claim 1, wherein the disiloxane has the following formula:

5. The process of claim 1, wherein the disiloxane has the following formula:

6. The process of claim 1, wherein the disiloxane has the following formula:

7. A light-sensitive photographic material having at least one supported silver halide emulsion layer containing a tetraalkyl-bis-aminomethyl disiloxane of the following formula:

in which R,, R R R represent hydrogen or alkyl having up to 12 carbon atoms; or R and R or R and R together may represent the ring members necessary for completing a pyrrolidine, morpholine, thiomorpholine, hexamethylene, imine or hexahydropyridine;

R stands for alkyl having up to six carbon atoms, in an amount ranging from 5 mg. to 5 g. per liter of emulsion.

8. The light-sensitive photographic material of claim 7, wherein R is methyl.

9. The light-sensitive photographic material of claim 7, wherein the emulsion contains 16 mg.-l6 g. of the disiloxane per mol silver halide.

10. The light-sensitive photographic material of claim 7, wherein the disiloxane has the following formula:

13. The light-sensitive photographic material of claim 7, wherein the disiloxane has the following formula: 

2. The process as defined in claim 1, wherein R5 is methyl.
 3. The process of claim 1, wherein the disiloxane has the following formula:
 4. The process of claim 1, wherein the disiloxane has the following formula:
 5. The process of claim 1, wherein the disiloxane has the following formula:
 6. The process of claim 1, wherein the disiloxane has the following formula:
 7. A light-sensitive photographic material having at least one supported silver halide emulsion layer containing a tetraalkyl-bis-aminomethyl disiloxane of the following formula:
 8. The light-sensitive photographic material of claim 7, wherein R5 is methyl.
 9. The light-sensitive photographic material of claim 7, wherein the emulsion contains 16 mg.-16 g. of the disiloxane per mol silver halide.
 10. The light-sensitive photographic material of claim 7, wherein the disiloxane has the following formula:
 11. The light-sensitive photographic material of claim 7, wherein the disiloxane has the following formula:
 12. The light-sensitive photographic material of claim 7, wherein the disiloxane has the following formula:
 13. The light-sensitive photographic material of claim 7, wherein the disiloxane has the following formula: 